This invention relates to fastening straps and more particularly to straps used in conjunction with orthopedic appliances and athletic equipment, the straps having synthetic material fastening elements which adhere when pushed together and a vinyl backing.
Straps used in conjunction with orthopedic wearing appliances and the like generally have interlockable hook and loop fastening elements. In one type, known as a face strap, one of the elements is attached to a first portion of the appliance and the other elements are adapted to pass through a ring fastened to a second portion of the appliance so that it may be drawn back toward the first portion and connect with the element on the first portion. In another type, known as a back strap, the hook and loop elements face in opposite directions and no ring is required. In either manner the two portions of the appliance may be securely connected together. For example, a brace or orthopedic corset may be so constructed to be adjustably worn by a patient or the like.
It is known in the prior art to use fasteners comprising synthetic materials which adhere when pressed together such as that sold under the trademark VELCRO, i.e., interlocking plastic hooks and tiny pile-like loops which effectively concatenate when pushed together to engage and which may be readily pulled apart to disengage. These fastening elements, hereinafter referred to as synthetic hook and loop fastener elements, in the prior art are bonded by ultrasonic means to backing strips of fabric textile material to form the strap, the ultrasonic process being such that relatively low heat is generated. However, such machines that exist for ultrasonic bonding can only bond one strap at a time and thus the process is very labor intensive. The large size of the machinery and the amount of power necessary to ultrasonically bond a number of such items in gang fashion has made this economically and functionally impractical. Thus, the cost of manufacturing such straps remains relatively high.
It is also known to bond various materials together utilizing radio frequency waves, i.e., dielectric bonding, wherein the material to be bonded acts as a dielectric between metallic elements of the bonding machinery. In this process heat is generated from the interior of the dielectric and flows outwardly in a manner similar to a microwave oven. When apparatus used for performing this process is utilized in conjunction with bonding of synthetic hook and loop fastener elements to fabric, the heat generated is such that burning of the fabric or melting of the synthetic hook and loop fastener elements occurs and this process cannot be utilized for producing conventional fastening straps.
Furthermore, since fastening straps of the type under consideration are used by individuals of various frame and structural sizes, the straps produced by the conventional ultrasonic means are manufactured in various sizes which must be stocked by the sellers. This creates large inventories of a relatively inexpensive product. The bond provided by the ultrasonic process is a spot or tack bond and the straps cannot be readily cut by the end user without fraying of the edges of the fabric material, especially if cut remote from a tack.